Papers by Keyword: Photocatalytic Efficiency

Abstract: Polymerization of styrene (St) stabilized by graphitic carbon nitride (g-C₃N₄) nanosheets, containing hydrophobic conjugated structure and hydrophilic oxygen-containing functional groups, is conducted at varying styrene concentration. It is found that the morphology of polystyrene (PS)/g-C₃N₄ nanocomposites tends to transform from g-C₃N₄ nanosheets coated PS nanospheres to g-C₃N₄ nanosheets separated by PS with irregular morphology by further increasing the concentration of St. The strong interaction between PS and g-C₃N₄ nanosheets, suggesting by FT-IR, XRD patterns and UV–vis spectra results, and the amount of St are responsible for the structure and morphology of the final product. The g-C₃N₄ nanosheets separated by PS exhibit the highest photocatalytic efficiencies towards degradation of methylene blue (MB), due to the specific structure and morphology. The PS separates g-C₃N₄ nanosheets, obstructs the aggregates of g-C₃N₄ nanosheets. On the other hand, the PS as a collector gathers the MB, which is benefit for the close contact between g-C₃N₄ nanosheets and MB, achieving the collective effect to greatly increase the photocatalytic efficiency.

Abstract: Using titaniferous blast-furnace slag (44-70 wt %), quartz, boric acid, and borax as the main raw materials, composition selecting in the phase-separation region of the Na2O-CaO-Al2O3-B2O3 -SiO2-TiO2 system, the basic glasses were prepared through mixed batches and melted at 1200 oC, then TiO2 whiskers could be achieved by heat-treatment the glass samples. The phase and morphology of samples were analyzed by XRD and SEM. The results indicated: when the composition of samples were selected in the phase-separation region and the ratio of SiO2/ B2O3 was between 1.64-1.87, at 850 °C heat-treatment, the diameter of whiskers was about 0.5μ~1μ and the length-diameter ratio was more than 50.

Abstract: AZO/TiO2 double-layered semiconductor coupled films were prepared through sequentially depositing AZO and TiO2 films on glass substrates by radio frequency (RF) magnetron sputtering. PVP-pretreatment and post-annealing were performed on these double-layers to achieve an exposure of the AZO buried-layer in different baring conditions. The photocatalytic efficiencies of these buried-layer bared structures were measured through dye decomposition under ultraviolet irradiation. Silver mirror reactions were operated to explore a possible photocatalytic mechanism associated with these buried-layer bared conditions. The buried-layer bared AZO/TiO2 coupled films present 2 ~3 times of photocatalytic activity comparing to the normal AZO/TiO2 double-layered or single layered ones. It suggested that the self-built electrical field formed from coupling semiconductors reduces the recombination of electron-hole pairs, increases the yield of surface photogenerated charges, and enhances the photocatalysis.

Abstract: Vanadium doped, nitrogen doped, and vanadium and nitrogen co-doped SrTiO3 powders with size of 20-30 nm in diameter were prepared by high energy milling method respectively. It was found that compared with those of pure SrTiO3, the photocatalytic activities of these three doped SrTiO3 samples for decomposing NO under visible light (λ>400 nm) and near ultraviolet light (λ>290 nm) irradiation were improved, and the co-doped sample exhibited the highest photocatalytic activity. 43.2% NO could be eliminated under the irradiation of light with wavelength larger than 400nm, about 3 times higher than that by pure SrTiO3. The photocatalytic activity of this sample near ultraviolet range is about 1.7 times higher than that of pure SrTiO3. The high visible light photocatalytic activity of this substance may be due to the high visible light absorption and large specific surface area.

Abstract: The anodic titania nanotubular films for photocatalyst were synthesized by anodic oxidation in HF electrolyte, and the photocatalytic properties of anodic TiO2 layer were investigated. The self organized anodic TiO2 film consisting of nanotubes with diameter of 100-150 nm as photocatalyst can be obtained by electrochemical method at a constant potential of 20 V for 40 min in HF solution. In order to improve the photocatalytic efficiency the anodic titania nanotube was heat treated at 550oC for 1h. In the evaluation of dye degradation, heat treated catalyst shows much higher efficiency than non-heat treated one.